Jack



Oct. 8, 1940. GUNN 2,217,403.

JACK

Filed Dec. 16, 1938 -IIIIII Patented on. s, 1940 UNITED STATES PATENTOFFICE JACK Earl G. Gunn, Racine, Wis.

Application December 16, 1938, Serial No. 246,043

or similar mechanisms of the type in which the load-carrying element isfrictionally held against movement relative to the supporting elementOne of the objects of my invention is to eliminate the danger in thepresent Jack" structures of this type, of the load getting out ofcontrol and dropping when the frictional hold is released.

A further object is to provide a means for releasing the frictional holdof the parts which is entirely controlled by the operator in a mannerwhich automatically prevents the accidental and uncontrolled lowering ofthe weight of the load.

A further object is the provision 'of a simple but completely effectiveoperator-controlled release means for Jacks of the friction holdingtype, whereby the operator cannot over-release the" device and cause theload to drop or fall unrestrictedly.

Other objects of my invention will appear from the accompanying drawingand the following description of the structure therein shown.

Fig. 1 is a view in elevation of a jack structure embodying myinvention;

Fig. 2 is an enlarged vertical section of the operating mechanism of thestructure shown in Fig. l, with its parts arranged for lifting orloadelevating purposes;

Fig. 3 is a view similar to said operating mechanism with the partsarranged for releasing or load-lowering purposes;

Fig. 4 is a transverse sectional view on the line 4-6 of Fig. 3; and

Fig. 5 is a transverse sectional view on the line 55 of Fig. 3.

My invention is applicable to any structure employing the principle offrictional gripping of one member for the purposes of moving and holdinganother member relatively thereto, but in order to illustrate theprinciple of my invention it is shown as being embodiedin a lifting jackcommonly known as an automobile jack.

This jack has a column or standard i upon which a load-carrying member 2is mounted to move lengthwise. The standard i is in the form of acylindrical rod supported in vertical position in a foot or base member3 having a socket 4 in which the end of the rod is inserted, these partsbeing readily separable for disassembly when the device is not in use.The load-carrying member 2 is in the form of an elongated sleeve freelymovable along the rod and having at its upper end a suitably shapedmember 5 to engage and carry the load to be raised or lowered, the loadbeing represented by an automobile bumper M.

The load-carrying member 2 has at its lower portion a lateral extensioni which bears upon one end of a holding member and which at the sametime forms a pivot or fulcrum about which the holding member is movable.The holding member I is of the usual type in devices of this characterand comprises a plate having a central opening a through which the rodstandard I ex- 1 tends and an extension 9 forming the and upon which theload member extension 0 beers. Another and opposite extension II has anopening ll through which an operating link I! e!- tends.

The bore or opening 8 of the holding member is slightly larger indiameter than the diameter of the rod standard 5, so that when theholding member is canted or rotated about a horizontal axis with respectto the longitudinal axis of the rod I the edges 8a of the opening 8frictionally grip the rod and thus hold the load at any height to whichthey are adjusted on the rod. A U- shaped spring l3, having one end in asocket bearing M of the load-carrying member 2 and its 25 other endbearing on the underside of the frictional holding plate extension 8,normally tends to urge and hold the frictional holding plate canted in adirection as shown in the drawing, so that the holding plate grips therod and holds the load against downward movement but allows theload-carrying member and plate to move freely upwardly along the rodstandard.

Power for lifting the load is applied to the loadcarrying member throughthe link i2 by means of an operating lever lb. The power arm of thelever is made in two sections. The short section l6 forms a socket intowhich the extension or handle ll of any desired length is inserted, thisbeing the usual construction in devices of this character and soarranged that the handle i'l may be moved or replaced as desired.

The inner end of this lever is pivotally connected at l8 to the lowerend of the link it. The upper end of the link is pivotally connected at19 to the load-carrying member 2. The link i2, however, has an elongatedslot 20 so that there will be some play in this pivotal connection for apurpose hereinafter described.

The operating lever I5 is pivotally mounted at H between upstanding lugs22 on the end of another friction plate 23, similar to the holding plateI. This control plate is movable vertically on the rod standard i, andthe edges of its openings through which the rod extends operates to ugrip the rod when the plate is canted or rotated about a horizontal axiswhich, in the present structure, is the pivot 2|. This control plate, inaccordance with my invention, is arranged to grip the rod in eitherdirection of movement, depending upon the position into which the plateis canted. It is yieldingly held in either of these positions by meansof the spring 24 which is carried by the rock shaft 25 mounted in thecontrol plate 23. The rock shaft 25 has an operating arm 26 by which itcan be rotated. It is held in either position by the spring button 21.In either position of the spring, one end bears yieldingly against therod standard and holds the control plate 23 in its correspondingposition. For instance, in Fig. 2, the parts are adjusted so that thecontrol plate 23 is canted to a position which causes the plate tofrictionally grip the rod and hold it against downward movement. This isthe position in which the jack operates to raise the load; that is, whenthe lever I5 is swung downward about its pivot 2 I, power is transmittedthrough the link I2 and the pivotal connection I9 to the load-carryingmember 2, which, together with the load, is moved upwardly on the rod.As soon as the lifting force is relieved by swinging the operating leverI5 upwardly, the holding plate I frictionally grips the rod and holdsthe load sustained in that position. The upward movement of theoperating lever raises the control plate member 23 on the rod and uponreverse movement .of the operating lever the member grips the rod inthat position.

In jacks ,of this character, it is the practice to utilize the removablehandle I! for releasing the holding plate and allowing the load tolower.

This is done by providing a socket member into which the end of theoperating handle I! is inserted and the parts are so arranged thatmovement of this hand lever then acts to pivot downwardly on the holdingplate I to release its frictional grip upon the rod I. This allows theload to move downwardly until the releasing pressure on the plate I isremoved. Since the handle I1, however, is in effect carried by theload-carrying member, it moves downwardly therewith and thus theoperator has no accurate control of the release. The result is thatfrequently the loadcarrying member will accidentally drop the entirelength of the rod and become very dangerous.

In accordance with my invention, I provide means for releasing theholding plate 2 independently of its relation to the load-carryingmember. As before mentioned, the link I2 has some play in its pivotalconnection I9 with the load-carrying member due to the elongated slot20. The link also has a laterally extending lug 28 which bears upon theupper side of the extension of the plate I, as shown clearly in Fig. 3.

Thus when the link I2 is moved downwardly by the operating lever, thelug 28 e'xerts pressure downwardly on the end of the holding member 1and rotates it in the reverse direction, causing the holding member 1 torelease its frictional grip upon the standard and allow the load andsaid plate to move downward. This releasing pressure or action of thelug 28 upon the holding plate! continues only so long as the lug. 28follows the plate I downwardly and continues to exert releasing pressurethereon. The instant, however, the downward movement of the lug 28 isstopped by stopping the movement of the operating lug, the holding platemoves downwardly away from said lug until the pressure is released.

The spring I3 then acts to again rotate the holding plate in thedirection which causes it to again grip the standard and hold theload-carrying member in that position against further downward movement.This downward releasing movement of the link I2 and its lug 28 isentirely independent of the load-carrying member because of the slottedpivotal connection of the link with the pivot I9. Thus the load-carryingmember can move downwardly only so long as the lug 28 exerts releasingpressure upon the holding member I, and the instant this pressure stops,the weight on the load-carrying member, together with the spring I3,automatically restores the holding member I to its holding position.

In Fig. 3 it will be noted that the control member 23 is in the reverseposition to that which is shown in Fig. 2. In this position the membergrips the rod standard I to hold said member against movement upwardlyon the rod, thus holding the pivot 2I of the operating lever stationaryso that the movement upwardly of the operating lever can exert adownward pull on the link I2 for releasing the holding member I. It willbe thus further noted that when the parts are in the relation shown inFig. 2, the reciproeating movement of the operating lever raises theload upwardly on the standard I in a step-bystep movement; that is,downward movement of the operating lever handle I! raises the link I2and through its pivotal connection I9 raises the load-carrying member 2a corresponding distance upwardly on the standard. The holding memberthen acts to hold the load-carrying member in that position while theoperating lever handle is swung upwardly.

It i obvious that changes may be made in the construction, arrangement,and operation of the various parts, without departing from the spirit Imember for releasing the engagement of the holding member with thestandard.

2. In a jack of the class described, the combination of a standard, aload-carrying member movable on said standard, a friction holding memberassociated with said load-carrying member and arranged to grip thestandard and hold the load-carrying member in any position to which itis moved on the standard, a friction control plate movable on saidstandard adjustable to grip the standard and hold itself againstmovement in either direction, an operating lever pivotally supported onsaid control plate and having means for applying power to saidloadcarrying member, and means associated with said lever and actingupon said friction holding member for releasing the holding member.

3. In a jack of the class described, the combination of a standard, aload-carrying member movable on said standard, a friction holding memberassociated with said load-carrying member and arranged to grip thestandard and hold the load-carrying member in any position to which itis adjusted on the standard, a friction control member movable on saidstandard adjustable to grip the standard and hold itself againstmovement in either direction, an operating lever pivotally mounted onsaid control member and having a link member for applying power to saidload-carrying member, said link member being arranged to act upon saidfriction holding member for releasing the holding member, and means foradjusting said control member to grip the standard in accordance withthe direction of movement of the load-carrying member on said standard,I

4. In a jack of the class described, the combination of a standard, africtional holding member and a frictional control member mounted onsaid standard and each adapted to grip the standard to hold said membersagainst movement, a load-carrying member supported by the holdingmember, an operating lever pivotally mounted on said control member andhaving means associated therewith for moving the loadcarrying memberupwardly on said standard, said means being operable by said operatinglever for releasing the holding member to' lower said load-carryingmember on the standard, and means for adjusting the control member tohold it against movement in either direction depending upon thedirection of movement of the loadcarrying member.

5. In a jack of the class described, the combination of a standard, aload-carrying member movable thereon and having associated therewith a.holding member adapted to frictionally grip the standard to hold theload-carrying member against movement in a downward direction when theholding member is canted in one direction, an operating lever mechanismindependently supported on said standard, and having means fortransmitting power to said load-carrying member for raising theload-carrying member on the standard, and means operated by said leverfor canting the friction holding member in the reverse direction torelease its gripping action upon the standard and permit theload-carrying member to move downwardly on the standard.

6. In a jack of the class described, the combination of a standard, aload-carrying member movable thereon and having associated therewith aholding member adapted to frictionally grip the standard to hold theload-carrying member against movement in a downward direction when theholding member is canted in one direction, a control lever supported onthe standard independently of the load-carrying member, and meansactuated by said control lever for canting said holding member in thereverse direction to release its grip upon the standard.

'7. In a jack of the class described, the combination of a standard, aload carrying member movable thereon and having associated therewith africtional holding member adapted to grip the standard to hold the loadcarrying member against movement in a downward direction, a

frictional gripping member on said standard,

means for adjusting said gripping member to frictionally hold thegripping member against movement in either direction, an operating leverpivotally mounted on said gripping member, and a link connected withsaid lever and. engaging the load carrying member to transmit powerthereto in an upward direction and having means to engage and releasethe frictional holding member in a downward direction.

EARL G. GUNN.

